An electrical junction box is a container for electrical connections, usually intended to conceal them from sight and deter tampering. A small metal, plastic, or fiberglass junction box may form part of an electrical conduit wiring system in a building, may be buried in the plaster of a wall, concealed behind an access panel, cast into concrete, mounted on a roof top, or free standing. The junction box may include terminals for joining wires. A similar container used for joining wires to electrical switches or sockets is called a pattress.
Because junction boxes and other similar enclosures are used to house electrical connections, they are a common source of fires. Thus, fireproofing may be provided around the incoming or outgoing wires or cables and may cover the junction box to help prevent short circuits inside the box during an accidental fire. Further, various techniques have been attempted to reduce the spread of a fire starting in a junction box or other electronics enclosure, or to prevent a fire external to a junction box or other electronics enclosure from spreading into the enclosure. Such techniques include using intumescent or meltable coatings or paints that expand or melt at elevated temperatures to cover ventilation openings, thus extinguishing afire by starving it of oxygen. In addition, typical junction boxes have no disconnecting means, which renders it difficult to suppress or extinguish DC arcing and/or fired, which often poses a threat to first responders.